Such a magnetic field sensor, known from EP 0525235 B1, has a self-compensation that obviates individual adjustment measures of the magnetic field sensor by means of a thermal and technological coupling of a Hall element and its supply devices. For this purpose, the corresponding elements are embodied jointly in an integrated circuit.
A further magnetic field sensor of the aforementioned type is known from DE 4431703 A1, wherein a magnetic field sensor is proposed which, besides a compensation of the offset of the Hall element, concomitantly takes account of the offset of the evaluation device connected downstream and thus enables a greater accuracy.
Hall elements are typical sensor elements which can be used to construct a magnetic field sensor and which usually interact in an array or a Hall element arrangement. A Hall element outputs a voltage signal in the magnetic field as a Hall signal if a current flows through it perpendicular to the magnetic field. The Hall signal, that is to say the Hall voltage, is dependent on the product of the vertical component of the magnetic flux density, the Hall current and the Hall constant. The Hall constant, which specifies the sensitivity of the Hall element, is material-dependent.
During operation in practice, a noise voltage composed of noise components of the Hall element and the downstream evaluation device is superposed on the useful signal of the Hall voltage formed from the Hall constant of the component, the vertical component of the magnetic flux density and the Hall current. Noise components of this type may result from temperature and material dependence.
Further components of the noise signal may arise from the concrete application. Thus, EP 0916074 B1 specifies a magnetic rotation sensor, in which a magnet mounted on an axis is arranged above a Hall element array. The Hall element arrangement itself comprises a number of individual sensor elements which are in a specific geometrical arrangement with respect to one another. The evaluation device connected downstream of the Hall element array determines the rotation angle of the axis from the Hall signal of the Hall element. Different temperature responses of the magnet and of the Hall element and also different distances between these two elements influence the useful signal, in particular. The distance between useful signal and noise signal is thereby altered.
If the Hall signal is digitized for the purpose of digital further processing, the dynamic range of the analog-to-digital converter that performs the digitization cannot be fully exhausted on account of the changes in the useful signal amplitude of the Hall signal.